Tumbling E Series ETDRS

Tumbling E charts, also referred to as Illiterate E tests, are useful for testing patients that are illiterate or mute. 
Patients simply have to sign or gesture which direction they see the E facing. 
Tumbling E charts are considered highly reliable and are second only to Landolt C tests. 
Both tests use only one optotype positioned differently and are useful for testing several types of patients.